Enhanced tribocorrosive properties of precipitation-hardened martensitic stainless steel by arc plasma nitriding

PH13-8Mo precipitation-hardened martensitic stainless steel was modified to improve its tribocorrosive properties by arc plasma nitriding. All treatments were conducted in an arc ion plating system at different nitriding temperatures. The results indicate that the thickness of the nitrided layer is in the range of 8.2–12.8 μm after a short nitriding duration. The predominant formation of expanded martensite (αN) with a small amount of iron nitrides is conducive to the increase in hardness, while the CrxN phase is precipitated at high nitriding temperatures. Low-temperature nitriding significantly inhibits the pitting of stainless steel, leading to enhanced corrosion resistance. The APN440 specimen demonstrates excellent tribocorrosion resistance against titanium alloy in a 3.5 wt. % NaCl solution. Therefore, arc plasma nitriding can be considered an effective method to enhance the tribocorrosive properties of PH13-8Mo steel in terms of high hardness, toughness, and corrosion resistance at a suitable nitriding temperature.